This invention relates to an improved cigarette filter with a scavenging effect on gas phase free radicals in cigarette smoke. The invention uses filters that contain proanthocyanidins for scavenging the free radicals. The present invention is also directed to a method for producing an improved cigarette filter with scavenging effect on gas phase free radicals.
It is well accepted that lit cigarettes produce an enormous amount of free radicals, including gas phase and solid phase free radicals. The number of free radicals in the gas phase has been estimated to be 1015 per puff, which are primarily alkyl, alkoxyl, peroxyl and nitric oxide (NO.) free radicals. Inhaling the gas phase free radicals produced by cigarette smoke into a human body is known to produce toxicological and pathological changes that are deleterious to humans. The gas phase free radicals are widely known to be more harmful to the human body than are solid phase free radicals. In part, this is a result of the high energy levels, that is, the volatility of gas phase free radicals.
Cigarette combustion, in particular, involves a complex burning process which produces free radicals that exist in the smoke. Cigarette smoke is a complex mixture of more than 4,700 chemicals, including high concentrations of highly reactive free radicals which play a major role in the toxicity of the smoke. The free radicals attack cell constituents, either directly or indirectly, and are believed to be a factor in tobacco smoke related diseases. Many parts of the body may be adversely affected by the gas phase free radicals including the lungs, mouth, pharynx, esophagus, heart and circulatory systems, and various organs. Free radicals may change the molecular structures of cell proteins and lipids and cause breaks in DNA sequences that lead to mutations, thereby increasing the risks of developing various types of cancers.
Studies indicate that mainstream smoke, that is, smoke inhaled directly from a lit cigarette and sidestream smoke, which is smoke emitted from the smoldering tobacco between puffs and through the exhaled smoke emitted by a smoker, contain high concentrations of free radicals. Sidestream smoke affects both the smoker and the non-smokers around the smoker. A major health concern relates to the exposure of non-smokers, including infants and children, to tobacco smoke in the home and other locations that derives from smokers. Individuals who do not smoke but are exposed to secondary sidestream smoke may suffer the consequences of free radical damage from tobacco smoke.
Most of the free radicals in burning cigarette-produced smoke gas phase are instantaneous and unstable. It is impossible to observe them directly with Electron Spin Resonance Spectroscopy (xe2x80x9cESR spectroscopyxe2x80x9d) techniques. In order to observe gas phase free radicals, such as those present in cigarette smoke, a spin capture technique is employed. In this technique, gas phase free radicals are captured and then transformed into a spin adduct which can be tested via ESR spectroscopy. A spin collector (PBN) collects smoke gas phase free radicals, which are predominantly alkoxyl free radicals (RO.) and alkyl free radicals (R.).
Most of the gas phase free radicals in tobacco smoke are RO. and alkyl R. free radicals. Nitrogenous substances oxidize and produce great amounts of NO free radicals (NO.) in the process of cigarette burning. A reaction of NO. with oxygen results in the production of reactive NO2. free radicals. A NO2. free radical may react with olefin, a substance produced during cigarette burning, to form alkyl free radical RO. RO. free radicals may attack cell membranes and cause lipid peroxidation. In turn, such lipid peroxidation may stimulate macrophages to release oxygen free radicals. Oxygen free radicals, on their own, may independently cause injury to cell constituents. They may poison cells and may contribute to causing lung cancer and heart disease together with the free radicals present in the smoke of a lit cigarette. Such free radicals may also attack and, thereby inactivate pulmonary xe2x88x9d-1 antiprotease, which inhibits elastase and hence causes pulmonary injury.
Also, free radicals from cigarette smoke are considered in the pathogenesis of smoking-induced lung diseases, such as emphysema, lung cancer and heart diseases. Components of the lung matrix itself (e.g. collagen, elastin) can be damaged and fragmented by oxidants in cigarette smoke.
The damage of free radicals from cigarettes is not limited to the pulmonary tract. It was found that the urine of smokers contains 10 fold higher amounts of a typical biomarker of oxidative damage than the amounts shown in the urine of non-smokers. The noxious pro-oxidant effects of smoking may even extend beyond the epicardial arteries to coronary microcirculation and affect regulation of myocardial blood flow and cause carotid-media thickness.
One filter that claims to scavenge free radicals in cigarette smoke was pursued jointly by Biophysics Institute of Academica Sinica and Beijing Cigarette Factory in 1995. It uses tea polyphenol, vitamin C, and active carbon for a compound filter. This filter scavenges approximately 14% of gas phase free radicals caused by tobacco smoke. If additional ingredients, including ematin, rutin, catechin and neo-rutin are added to the tobacco in the cigarette, approximately an additional 12% of the gas phase free radicals may be scavenged. These additional ingredients, in combination, are referred to as xe2x80x9ckendirxe2x80x9d and xe2x80x9capocynum venetum Lxe2x80x9d. Another cigarette filter that scavenges for free radicals was jointly invented by the Greece Golden Filter Company and Filter Development Company in 1999 (the xe2x80x9cjointly developed filterxe2x80x9d). This filter comprises active carbon and hemoglobin. It claims to scavenge about 90% gas phase free radicals found in tobacco smoke. Neither one of these two filters has gained commercial acceptance by cigarette manufacturers. There are two major reasons for the poor commercial acceptance of these filters. One is that the large dosages of additives in these filters reduce the original smoke flavor of the cigarette. This is a very significant disadvantage in the cigarette industry where cigarette taste and flavor is a key selling feature of recognized cigarette brands. Another factor is that the production of these complex filters requires a large investment in equipment modification which cigarette manufacturers are reluctant to invest. Another filter disclosed in U.S. Pat. No. 5,829,449 is directed to using L-glutathione and a source of selenium as the radical scavenger complex ingredient.
Accordingly, there is a need for: i) a cigarette filter with good scavenging effect on gas phase free radicals in cigarette smoke; ii) a cigarette filter that scavenges gas phase free radicals in cigarette filters and does not significantly alter or reduce the flavor and taste of the cigarette; and iii) a cigarette filter containing free radical scavengers that are optimally exposed to cigarette smoke in order to yield a maximum scavenging effect in a short period of time.
One aspect of the invention resides in an improved cigarette filter with a scavenging effect on smoking induced gas phase free radicals which is achieved through the addition of an effective amount of a filtering ingredient or a mixture of the filtering ingredient and vitamin C and/or other ingredients known in the art having antioxidant filtering properties, but excluding a certain amount of L-glutathione. The filtering ingredient is selected from a group consisting of proanthocyanidins which may include procyanidins. These ingredients include extracts of barks of pine trees, extracts of cones of cypress trees, extracts of grape seeds and any combination thereof.